czm_material czm_getMaterial(czm_materialInput materialInput)
{ 
  czm_material material = czm_getDefaultMaterial(materialInput); 
  vec2 st = materialInput.st;

  vec4 colorImage = texture2D(image, vec2(fract(2.0 * st.s - time), st.t));
  material.alpha = colorImage.a * color.a;
  
  material.diffuse = (colorImage.rgb + color.rgb) / 0.7;

  return material;
}